Wear monitoring device and method of monitoring undercarriage and roller wear

ABSTRACT

An undercarriage monitoring device has a roller assembly including a fixed roller component and a bushing. An opening is formed within the fixed roller component. A first sensor is disposed within the opening of the fixed roller component over the bushing. The first sensor is configured to sense a first physical characteristic of the bushing. The fixed roller component is a shaft or a housing. The first sensor is a temperature sensor or a Hall effect sensor. A magnet is disposed on the roller assembly. A second sensor is disposed within the opening of the fixed roller component over the bushing. The second sensor is configured to sense a second physical characteristic of the bushing. A data transmitting device is coupled to the first sensor. Data is collected from the sensor. The data collected from the sensor is transmitted to a receiving device.

CLAIM TO DOMESTIC PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 13/835,626, now U.S. Pat. No. 10,046,815, filed Mar. 15, 2013,which claims the benefit of U.S. Provisional Application No. 61/616,110,filed Mar. 27, 2012, which applications are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates in general to undercarriage structures formining and construction equipment, more particularly, to a method ofmonitoring the wear on an undercarriage.

BACKGROUND OF THE INVENTION

Mining, construction, forestry, agriculture, landscaping, and materialhandling industries use a variety of heavy equipment for moving earthand other materials. Hydraulic and electric excavators, backhoes,shovels, and drills are examples of equipment commonly used at, forexample, mining or construction sites. The pieces of equipment areheavy-duty equipment, which are mobile and some are capable of movingthousands of kilograms of material at a time. The drive systemunderneath heavy equipment may include axles with wheels or a track-typeundercarriage. A track undercarriage is used to move the heavy equipmentand large amounts of material over many types of terrain. Trackundercarriages are intended to operate on a variety of terrainconditions and can handle a higher operating weight capacity thancomparably sized wheeled assemblies.

Track undercarriages include a track located on each side of a piece ofheavy equipment underneath the equipment in a similar location to wherewheels are located on wheeled equipment. A track undercarriage is usedin place of wheels and operates with a drive mechanism to rotate thetrack to propel the heavy equipment. Each track on either side of theequipment rotates around an oblong undercarriage frame. The track ismade up of a series of individual track shoes linked together in acontinuous chain. The track undercarriage includes a series of rollerswhich allow the track to rotate about the undercarriage frame. Rollersinclude lower rollers or track rollers, upper rollers or carrierrollers, and idler rollers.

The track rotates around an undercarriage frame and is driven by asprocket. The sprocket is located on one end of the track, typically therear, and an idler roller supports the opposite end of the track,typically the front. In between the idler and sprocket, a plurality ofrollers supports the undercarriage frame and rotates as the trackrotates around the undercarriage frame. Rollers provide a low frictionsurface for the track to move along as the heavy equipment moves alongthe terrain. Rollers can be located above and below the undercarriageframe on the track. A track moves over the sprocket, over the upperrollers, around the idler at the front of the undercarriage, then underthe lower rollers where the track also contacts the ground. Anundercarriage typically includes at least one upper roller and severallower rollers. A large shovel, for example, may have two upper rollers,and idler roller, and seven or eight lower rollers. The rollers are loadbearing, with some rollers being stressed by the weight of the heavyequipment more than other rollers. The rollers are metal and aretypically made of steel and include metal bushings or bearings,typically made of bronze, to reduce friction between parts of the rollerassembly.

The roller bushings are located inside the roller assembly and arelubricated in order to allow rollers to rotate with less friction.Roller assemblies may be designed with the bushing fixed, for example,within an end cap in which the roller rotates within the bushing. In analternative design, the bushing is fixed within the roller body and boththe bushing and roller body rotate around a shaft. Ideally, rollerassemblies and bushings are well-lubricated and to maintain alow-friction contact surface between the bushing and the roller orbetween the bushing and shaft. Inadequate lubrication of the contactsurfaces increases friction between the bushing and roller assemblywhich wears down the bushing eventually causing damage to the rollerassembly. Even with adequate lubrication, bushings are subject to stressfrom contact with the roller or shaft and wear out over time. Becausebushings and lubricant are internal to a roller assembly, the wearstatus of the bushings and amount of lubricant within the rollerassembly are difficult to monitor.

Roller assemblies within a track undercarriage typically fail due tolack of adequate lubrication. Without adequate lubrication, frictionbetween the rollers and bushings or bushing and shaft increasessubstantially and causes wear to the components. One indicator ofinadequate lubrication is increased heat within the roller assembly. Acurrent approach to monitoring rollers requires a person to measure thetemperature of the rollers by walking next to the equipment as theequipment is driven and take periodic temperature readings of therollers using a laser-sighted infrared gun-style thermometer. Thecurrent approach is dangerous for the person taking temperaturemeasurements, because the measurement device requires the person toremain in close proximity to the heavy equipment while the equipment isoperating. Further, manual monitoring of roller temperature requiresexpensive labor, and roller temperature is simply not monitored duringeveryday operation of the heavy equipment. Another approach to managinga track undercarriage is to inspect and repair components during apre-scheduled preventative maintenance of the equipment. Often,lubricant and bushings wear out or problems occur before the periodicmaintenance.

Without constant monitoring of the roller assemblies on a trackundercarriage, lubricant problems go unnoticed and bushings tend to weardown completely before the wear is noticed leaving rollers without anybushings. If a bushing wears down completely and a roller continues torun without a bushing, damage occurs to the roller as the rollercontacts other surfaces within the roller assembly. The metal on metalor steel on steel contact between the roller and other roller assemblycomponents results in the surface of the roller and other components towear and deteriorate beyond the point at which the parts can berepaired. Eventually, a roller without lubricant or a bushing will weardown and stop turning altogether. A track undercarriage is likely tobreak down at the point of use when a roller stops turning unexpectedly.Equipment that breaks down at a work site creates additional hazards andmaintenance problems in addition to adding cost to repairs andreplacements. However, if lubricant problems or bushing wear is caughtearly, a roller assembly can be repaired. Repair of roller assemblycomponents is less expensive than replacement with a new rollerassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a portion of a track undercarriage including rollers;

FIG. 2 illustrates a roller for a track undercarriage which can bemonitored with a sensor;

FIG. 3 illustrates a roller assembly including a monitoring device;

FIG. 4 illustrates a roller bearing which can be monitored with amonitoring device;

FIG. 5 illustrates a roller assembly end cap including a monitoringdevice disposed within the end cap;

FIG. 6 illustrates a cross section of a roller assembly including aroller, a bearing, and a monitoring device;

FIG. 7 illustrates further detail of a cross section of a roller, abearing, and a monitoring device;

FIG. 8 illustrates a cross section of a roller assembly including aroller, a bearing showing wear, and a monitoring device;

FIG. 9 illustrates further detail of a cross section of a rollerassembly including a roller, a bearing showing wear, and a monitoringdevice;

FIG. 10 illustrates an alternative embodiment of a roller assemblyincluding a monitoring device disposed within the shaft;

FIG. 11 illustrates an alternative embodiment of a roller assembly withdual flanges and including a monitoring device;

FIG. 12 illustrates a cross section of an alternative roller assemblywith a monitoring device disposed within the shaft;

FIG. 13 illustrates further detail of a cross section of an alternativeroller assembly with a monitoring device disposed within the shaft;

FIG. 14 illustrates an alternative embodiment of a roller assembly withan idler roller and including a monitoring device;

FIG. 15 illustrates a cross section of an idler roller including amonitoring device; and

FIG. 16 illustrates further detail of a cross section of an idler rollerincluding a monitoring device.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the Figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Monitoring the operational state of an undercarriage internally is amore effective way to determine wear and prevent undercarriage damagethan monitoring the external condition of an undercarriage. Internalmonitoring of undercarriage wear allows deterioration of lubricant orbearings to be detected within a roller assembly before a roller isdamaged. Early detection of lubricant problems and bearing wear throughconstant monitoring allows lubricant and bearings to be replaced orrepaired before irreparable damage is done to a roller. Repairing orrebuilding a roller assembly is less expensive than replacing a roller,but repair of the roller assembly is available only before damage isdone to the roller. Maintaining lubricant and bearings prevents damageto the roller assembly. Therefore, detecting lubricant problems andbearing wear earlier leads to less costly maintenance of anundercarriage.

In order to know when lubricant and bearings within a roller assemblyneed maintenance, an internal monitoring system is beneficial. Aninternal monitoring system of an undercarriage allows the presentoperational state inside the roller assembly to be monitored so thatroller assembly parts can be repaired before the roller is damaged andneeds to be replaced. Therefore, an internal monitoring system forroller assemblies is described herein.

FIG. 1 illustrates a portion of a track undercarriage including rollerswhich are monitored with a monitoring device. The portion ofundercarriage 10 shown in FIG. 1 is part of a track type undercarriageand can be incorporated into an undercarriage for many types of heavyequipment, such as a hydraulic and electric excavator, backhoe, shovel,drill, or other machine, including a tank. A complete undercarriagetypically includes two track portions with one track portion disposed oneach side of the complete undercarriage. Undercarriage 10 can be adifferent size or configuration in order to fit different types of heavyequipment for different industries or uses. Undercarriage 10 includes asprocket 12 at rear 14 of undercarriage 10 and an idler 16 at front 18of undercarriage 10. Undercarriage 10 includes a plurality of upperroller assemblies or upper rollers 20. Two upper rollers 20 are depictedin FIG. 1. Undercarriage 10 includes a plurality of lower rollerassemblies or lower rollers 22. Seven lower rollers 22 are depicted inFIG. 1. However, undercarriage 10 can be designed with fewer oradditional upper rollers 20 and lower rollers 22. Track 24 is made up ofindividual track shoes 26 linked together in a continuous chain. Track24 is disposed around sprocket 12, idler 16, upper rollers 20, and lowerrollers 22. Track 24 rotates in both the clockwise and counterclockwisedirections around sprocket 12, idler 16, upper rollers 20, and lowerrollers 22.

An undercarriage frame, not shown in FIG. 1, supports the upperstructure of heavy equipment. The undercarriage frame includes a frameportion which fits within track 24 of undercarriage 10. The body of theexcavator, backhoe, shovel, drill, or other equipment is coupled to theundercarriage frame. The undercarriage frame may include any stylenecessary to support the equipment, such as an H-style body, asquare-style body, or other body style. The upper structure of theequipment is disposed on an undercarriage frame which is driven ormobilized by undercarriage 10. The portion of the undercarriage framewhich fits within undercarriage 10 couples to or contacts idler 16,upper rollers 20, and lower rollers 22. Track 24 rotates around theundercarriage frame to mobilize undercarriage 10. The weight of theundercarriage frame and upper structure of the heavy equipment issupported by the plurality of rollers which roll as track 24 rotates tomove undercarriage 10.

Undercarriage 10 withstands a significant amount of weight, stress, andwear under normal operating conditions. Over time, components ofundercarriage 10 wear out and must be repaired or replaced. Rollers,such as idler 16, upper rollers 20, and lower rollers 22 each includebushings and lubricant which are internal to the rollers. The wear anddamage caused by worn out bushings and inadequate lubrication isdifficult to determine by visual or physical inspection of the rollerswhile the rollers are mounted to undercarriage 10. Therefore, aninternal monitoring device is used to monitor the wear and operationalstate of the lubricant and bushing within each roller. A monitoringdevice including sensor or sensors allows a roller to be monitoredconstantly rather than while the equipment is running during dailyoperation. A monitoring device is disposed on or within each rollerassembly on undercarriage 10. The monitored roller assemblies includeidler 16, upper rollers 20, and lower rollers 22.

FIG. 2 illustrates a roller which can be monitored with a monitoringdevice. Roller body 30 is a part of a roller assembly which facilitatesthe movement of track 24 around the undercarriage frame. Roller body 30is an example of a roller with a solid roller body in which roller body30 is one piece. Roller body 30 includes a single flange 32. In analternative embodiment, roller body 30 includes dual or multipleflanges. In another embodiment, roller body 30 is configured to rotatearound a shaft. Track 24 makes contact with roller body 30 at surfaces34 and 36 adjacent to flange 32. Roller body 30 includes end 38 and end40 opposite to end 38. Ends 38 and 40 of roller body 30 are eachconfigured to fit within an end cap of a roller assembly. End 38 ofroller body 30 includes surface 42, and end 40 includes surface 44.Roller body 30 can be metal, such as high strength steel, hardenedsteel, carbon steel, metal alloy, or other material. In one embodiment,roller body 30 is hardened steel. Roller body 30 is monitored with themonitoring device disposed within the roller assembly to detect wearwithin the roller assembly before roller body 30 is damaged.

FIG. 3 illustrates roller assembly with a roller and sensors mountedwithin end caps. Roller assembly 50 includes roller body 30, end caps 52and 54, bushings 56, and monitoring devices 58. A portion of rollerassembly 50 is cut away in FIG. 3 to show internal components of rollerassembly. Roller body 30 is partially disposed within and isrotationally coupled to end caps 52 and 54. End caps 52 and 54 havesimilar structures, and features described of end cap 52 or 54 apply toboth end caps 52 and 54. End caps 52 and 54 constitute a housing foreach of ends 38 and 40 of roller body 30. End caps 52 and 54 are rigidlyattached to or mounted to the undercarriage frame and roller body 30 ismounted to the undercarriage frame by end caps 52 and 54. End caps 52and 54 can be metal, including high strength steel, hardened steel,carbon steel, metal alloy, or other metal. End caps 52 and 54 include aplurality of openings or drilled holes for accommodating fasteners andother roller assembly components. Openings 64 is formed through surface60 of end cap 52. Opening 66 is similar to opening 64 and is formedthrough surface 62 of end cap 54. Openings 64 and 66 in end caps 52 and54, respectively, allow lubricant to flow into the inside of end caps 52and 54 to lubricate bushings 56 and surfaces 42 and 44 at ends 38 and 40of roller body 30.

Bushings 56 are disposed within end caps 52 and 54 of roller assembly50. Bushing 56 constitutes a bearing disposed between end 38 of rollerbody 30 and end cap 52 to reduce the friction between roller body 30 andend cap 52. In one embodiment, bushing 56 is fixed within end cap 52.Roller body 30 rotates within end cap 52 and bushing 56. A bushingsimilar to bushing 56 is fixed within end cap 54 at the end 40 of rollerbody 30. Bushing 56 allows roller body 30 to turn or rotate within endcaps 52 and 54 without damaging roller body 30 or end caps 52 and 54 byreducing friction between roller body 30 and end caps 52 and 54.

Bushings 56 include inner surface 70 which contacts surface 42 of rollerbody 30 at end 38 of roller body 30. A lubricant is disposed betweensurface 42 of roller and surface 70 of bushing 56 to reduce the frictionbetween surface 42 of roller body 30 and inner surface 70 of bushing 56.The lubricant between roller body 30 and bushing 56 reduces the frictioncaused by roller body 30 rotating within end cap 54. In an automaticlubrication system, lubricant is regularly pumped through openings 64and 66 into end caps 52 and 54 to lubricate bushing 56 and roller body30 while undercarriage 10 is driving and roller body 30 is rotating. Anopening is formed through bushing 56 to allow lubricant to reach innersurface 70 of bushing 56. In a self-contained lubrication system,lubricant is sealed inside the roller assembly. In either the automaticlubrication system or the self-contained lubrication system, thequantity and quality of lubrication between inner surface 70 of bushing56 and surface 42 of roller body 30 is monitored while roller assembly50 is mounted to the undercarriage frame using monitoring device 58.Monitoring device 58 can be incorporated into a lubrication system inorder to monitor the lubrication and bushing wear within end cap 54.Alternatively, monitoring device 58 is separate from the lubricationsystem and can be incorporated into existing roller assemblies.

Opening 72 is formed completely through end cap 52 extending fromsurface 60 to an inner surface 74 of end cap 52. Monitoring device 58 isdisposed within opening 72. Monitoring device 58 includes one or moresensors to measure one or more physical characteristics of bushing 56,roller body 30, and the lubricant. Opening 72 is formed with a diameterD appropriate to fit monitoring device 58. In one embodiment, diameter Dof opening 72 is approximately 1.8 centimeters (cm), or 0.7 inches. Inan alternative embodiment, opening 72 can be formed with a diametergreater than or less than 1.8 cm. Opening 72 is formed with a diameterlarge enough to accommodate monitoring device 58. In an alternativeembodiment, additional openings are formed partially or completelythrough end cap 52 to accommodate additional components of monitoringdevice 58. Opening 72 is formed such that opening 72 does not degradethe strength and functionality of end cap 52. In an alternativeembodiment, opening 72 is formed through a surface of end cap 52 otherthan surface 60.

Opening 76 is similar to opening 72 and is formed completely through endcap 54 extending from surface 62 to an inner surface of end cap 54 tomonitor the bushing within end cap 54. A second monitoring device 58 isdisposed within opening 76. Monitoring device 58 includes one or moresensors to measure one or more physical characteristics of bushing 56,roller body 30, and the lubricant. Opening 76 is formed with a diameterappropriate to fit monitoring device 58. In one embodiment, the diameterof opening 76 is approximately 1.8 centimeters (cm), or 0.7 inches. Inan alternative embodiment, opening 76 can be formed with a diametergreater than or less than 1.8 cm. Opening 76 is formed with a diameterlarge enough to accommodate monitoring device 58. In an alternativeembodiment, additional openings are formed partially or completelythrough end cap 54 to accommodate additional components of monitoringdevice 58. Opening 76 is formed such that opening 76 does not degradethe strength and functionality of end cap 52. In an alternativeembodiment, opening 76 is formed through a surface of end cap 54 otherthan surface 62.

FIG. 4 illustrates a bushing which is monitored with a monitoringdevice. Bushing 56 may include opening 80 extending from outer surface82 to inner surface 70 to facilitate lubricant flow. Bushing 56 can bemetal, including copper, tin, zinc, nickel, iron, aluminum, or othermetal or can be metal alloy such as copper and tin, known as bronze,copper and zinc, or other metal alloy. In one embodiment, bushing 56 isbronze, a nonferrous metal, and is a softer metal than roller body 30and end cap 52. When bushing 56 is new, bushing 56 has a thickness T1which is the thickness of a new bushing without wear. Bushing 56 ismonitored by monitoring device 58 while bushing is disposed withinroller assembly 50 which is mounted within undercarriage 10.

FIG. 5 illustrates an end cap of a roller assembly including amonitoring device disposed within the end cap. End cap 54 is part ofroller assembly 50 and accommodates a roller body 30. Opening 84 in endcap 54 is formed partially or completely through end cap 54 toaccommodate roller body 30. Additional openings are formed through endcap 54 to accommodate fasteners and other functions. Opening 66, forexample, is formed completely through surface 62 of end cap 54 and actsas a lubricant delivery opening. Opening 76 is formed completely throughsurface 62 of end cap 54. Opening 76 provides a location for monitoringdevice 58 to be housed within end cap 54. In one embodiment, monitoringdevice 58 is disposed completely or partially within opening 76. In analternative embodiment, additional openings are formed partially orcompletely through end cap 52 and monitoring device 58 includes a sensordisposed within a first opening and an additional component, such as amagnet, disposed in a second opening. Monitoring device 58 is furthercoupled to wiring and circuitry to enable data from monitoring device 58to be stored and transferred. The wiring and circuitry may be disposedwith opening 76 or within other openings in end cap 54 or may be mountedto end cap 54 or roller assembly 50.

Returning to FIG. 3, end caps 52 and 54 constitute the parts of rollerassembly 50 which couple to roller body 30. Each of end caps 52 and 54include monitoring device 58 disposed within the end caps which act as ahousing or a mounting point for monitoring device 58. A monitoringdevice 58 is placed within each of openings 72 and 76 in close proximityto bushings 56 or in contact with bushings 56. Monitoring device 58 mayinclude one sensor or multiple sensors. In one embodiment, multiplesensors are accommodated within monitoring device 58 which is formedinto one unit and fits within openings 72 and 76. In an alternativeembodiment, additional openings similar to openings 72 and 76 are formedcompletely or partially through end caps 52 and 54 to accommodatemultiple monitoring devices 58 or multiple sensors or components ofmonitoring device 58.

Monitoring device 58 monitors a physical characteristic of rollerassembly 50 in order to detect a problem within roller assembly 50.Monitoring device 58 measures temperature of roller assembly 50 andthickness of bushing 56, determines the presence or absence of lubricantwithin roller assembly 50, and determines if bushing 56 has been worncompletely away. Monitoring device 58 includes a sensor such as a Halleffect sensor, temperature sensor, particulate sensor, viscosity sensor,depth sensor, or other type of sensor. In one embodiment, monitoringdevice 58 measures a temperature at a surface of bushing 56 or atemperature within end cap 52. In an alternative embodiment, monitoringdevice 58 measures thickness of bushing 56 using a magnet and a Halleffect sensor. In another embodiment, monitoring device 58 includes botha temperature sensor and a Hall effect sensor with a magnet. Thetemperature sensor, Hall effect sensor, and magnet of monitoring device58 fit within openings 72 and 76 in end caps 52 and 54 respectively. Endcaps 52 and 54 can be configured with additional openings or ports toaccommodate additional sensors and other components of monitoring device58. In one embodiment, a temperature sensor is disposed in a firstopening and a Hall effect sensor is disposed in a second opening. Inanother embodiment, a Hall effect sensor is disposed in one opening anda magnet is disposed in a second opening such that the sensor isdisposed between bushing 56 and the magnet.

In one embodiment of monitoring device 58, a temperature sensor is usedto determine the lubricant status within roller assembly 50. Increasedtemperature within roller assembly 50 is one indicator of inadequatelubrication of bushing 56. A temperature sensor is disposed within ormounted to roller assembly 50 to measure the temperature of rollerassembly 50 within end caps 52 and 54. When lubrication runs low or runsout, the friction between surface 42 of roller body 30 and inner surface70 of bushing 56 increases. Without lubricant, surface 42 of roller body30 directly contacts inner surface 70 of bushing 56. Roller body 30 andbushing 56 are metal, resulting in metal on metal contact. The increasedfriction between roller body 30 and bushing 56 results in increasedtemperature at roller body 30 and bushing 56 within end caps 52 and 54.The change in temperature caused by reduced lubrication or a lack oflubrication is detected or sensed by the temperature sensor ofmonitoring device 58. The temperature sensor may include a contactsensor, such as a thermocouple, thermistor, resistance temperaturedetector (RTD), or a non-contact temperature sensor, such as an infraredheat sensor. In an alternative embodiment, monitoring device 58 measuresthe viscosity of the lubricant to determine the quality of lubricationwithin roller assembly 50. In another embodiment, monitoring device 58includes a particulate sensor to determine the quality of lubricationand amount of metal particulates within roller assembly 50.

FIG. 6 illustrates a cross section of a roller assembly including aroller, a bearing, and a monitoring device. End cap 54 includes bushing56 fixed on inner surface 74 of end cap 54. In a fixed bushing design,roller body 30 rotates within bushing 56 and end cap 52. Opening 76 or aplurality of openings 76 is formed through end cap 52 to provide ahousing for monitoring device 58. Monitoring device 58 is disposedwithin opening 76 or various components of monitoring device 58 aredisposed in multiple openings. Monitoring device 58 includes at leastone sensor, such as a Hall effect sensor, temperature sensor,particulate sensor, viscosity sensor, depth sensor, or other type ofsensor.

In one embodiment of monitoring device 58, Hall effect sensor 92 is usedto measure a thickness of bushing 56 to determine the amount of wear onbushing 56. Monitoring device 58 includes magnet 90 and Hall effectsensor 92. Hall effect sensor 92 is disposed within opening 76. In oneembodiment, magnet 90 is disposed within opening 76 over Hall effectsensor 92 such that Hall effect sensor 92 is disposed between magnet 90and bushing 56. Bushing 56 is disposed between Hall effect sensor 92 androller body 30. A Hall effect sensor includes a transducer whichresponds to a magnetic field by producing a voltage. Hall effect sensor92 responds to the magnetic field between magnet 90 and roller body 30.In roller assembly 50, bushing 56 is typically bronze, a similar copperalloy, or other alloy or metal. Bronze is a non-ferrous metal and isunaffected by a magnet. Roller body 30 is typically hardened steel, orother type of steel or metal. Steel is a ferrous material and isattracted to a magnet. Therefore, roller body 30 responds to magnet 90and bushing 56 is unaffected by magnet 90. The magnetic field betweenmagnet 90 and roller body 30 passes through the non-ferrous bushing 56in between magnet 90 and roller body 30. The distance between rollerbody 30 and magnet 90 determines a magnetic field at Hall effect sensor92 which is converted into a voltage by Hall effect sensor 92. Thethickness of bushing 56 determines the distance between roller body 30and magnet 90 because bushing 56 separates roller body 30 from end cap54 where magnet 90 is located. The magnetic field between roller body 30and magnet 90 changes when bushing 56 wears down and becomes thinner androller body 30 moves closer to or farther away from magnet 90.Therefore, monitoring device with magnet 90 and Hall effect sensor 92detects the amount of wear on bushing 56 by indirectly measuring thethickness of bushing 56.

In an alternative embodiment of monitoring device 58, Hall effect sensor92 is disposed on one side of bushing 56 and magnet 90 is disposed on aside of bushing 56 opposite the side where Hall effect sensor 92 isdisposed. Bushing 56 is disposed between magnet 90 and Hall effectsensor 92. The magnetic field of magnet 90 passes through bushing 56 andis sensed by Hall effect sensor 92. For example, Hall effect sensor 92is disposed within opening 76 and magnet is not disposed within opening76, but is disposed in an opening formed through end 40 of roller body30 or is disposed within bushing 56. As the thickness of bushing 56changes, the position of Hall effect sensor 92 changes with respect tomagnet 90. As Hall effect sensor 92 moves closer to or is positionedcloser to magnet 90, the magnetic field increases and the voltageproduced by Hall effect sensor 92 increases. As Hall effect sensor 92moves farther from or is positioned farther away from magnet 90, themagnetic field decreases and the voltage produced by Hall effect sensor92 decreases. Therefore, monitoring device with magnet 90 and Halleffect sensor 92 detects the amount of wear on bushing 56 by directlymeasuring the thickness of bushing 56.

FIG. 7 shows further detail of the cross section in FIG. 6 of a roller,a bearing, and a monitoring device. Roller body 30 is disposed in closeproximity to or in contact with bushing 56. A thin layer of lubrication,if present, separates surface 42 of roller body 30 and inner surface 70of bushing 56. During normal operation, roller body 30 rotates smoothlywithin bushing 56 along inner surface 70 of bushing 56. A thickness T1of bushing 56 is the thickness of a new, unworn, and undamaged bushing.In one embodiment, monitoring device 58 is disposed on outer surface 82of bushing 56 within opening 76 in end cap 54. In another embodiment,Hall effect sensor 92 is disposed in opening 76 and magnet 90 isdisposed in an additional opening adjacent to opening 76 in end cap 54.Hall effect sensor 92 produces a voltage which correlates to bushingthickness T1 or the distance between surface 42 of roller body 30 andmagnet 90. In an alternative embodiment, magnet 90 is disposed on oneside of bushing 56 and Hall effect sensor 92 is disposed on an oppositeside of bushing 56. Hall effect sensor 92 produces a voltage whichcorrelates to bushing thickness T1 or to the distance between Halleffect sensor 92 and magnet 90. When magnet 90 is disposed within or onroller body 30, Hall effect sensor 92 produces a voltage whichcorrelates to the distance between Hall effect sensor 92 and roller body30 where magnet 90 is located. In each embodiment, monitoring device 58functions even while roller body 30 is moving or rotating. Monitoringdevice 58 produces output data which indicates the bushing thicknessthereby reporting an operational state of bushing 56 in real-time.

FIG. 8 shows a cross section of a roller assembly including a roller, abearing showing wear, and a monitoring device. Roller body 30 isdisposed within end cap 54 and bushing 56. Bushing 56 is fixed withinend cap 54. Roller body 30 spins or rotates within end cap 54 andbushing 56. Roller body 30 includes surface 42 which contacts innersurface 70 of bushing 56 as roller body 30 spins. Under ideal operatingconditions, lubricant is disposed within end cap between surface 42 ofroller body 30 and inner surface 70 of bushing 56. Without adequatelubrication, roller body 30 grinds against bushing 56 with increasedfriction causing increased heat within end cap 54 and causing bushing 56to be worn away. Bushing 56 is typically bronze or a softer metal thanroller body 30. Roller body 30 rubs bushing 56, wearing down bushing 56at inner surface 70 as roller body 30 spins without lubrication. Whenbushing 56 is worn down by roller body 30, bushing 56 becomes thinner.Thickness T2 indicates the reduced thickness of bushing 56 as a resultof wear on bushing 56 by roller body 30.

FIG. 9 shows further detail of the cross section in FIG. 8 of a rollerassembly including a roller, a bearing showing wear, and a monitoringdevice. Without adequate lubrication or simply over time, surface 42 ofroller body 30 wears on inner surface 70 of bushing 56. Roller body 30presses against inner surface 70 of bushing 56, so when bushing 56 isthinned, roller body 30 no longer fits properly within bushing 56.Roller body 30 may move closer to or farther away from inner surface 74of end cap 54.

In one embodiment, when bushing thickness T1 is reduced to thickness T2,roller body 30 changes position relative to inner surface 74 of end cap54 and to magnet 90. The magnetic field at Hall effect sensor 92increases as roller body 30 moves closer to magnet 90, and decreases asroller body 30 moves farther from magnet 90. Hall effect sensor 92produces a higher or lower output voltage which correlates to theposition of roller body 30 due to the reduced thickness of bushing 56.The magnetic field at Hall effect sensor 92 changes as bushing 56changes thickness compared to bushing thickness T1. The difference inthe Hall effect between new bushing 56 and worn bushing 56 correlates tothe difference between thickness T1 and T2. An output voltage of Halleffect sensor 92 is thereby used to monitor the thickness of bushing 56.

In an alternative embodiment, magnet 90 is disposed on one side ofbushing 56 and Hall effect sensor 92 is disposed on an opposite side ofbushing 56. Hall effect sensor 92 produces a voltage which correlates tothe distance between Hall effect sensor 92 and magnet 90 whichcorrelates to the thickness of bushing 56. When bushing 56 wears downand becomes thinner, the distance between Hall effect sensor 92 andmagnet 90 increases or decreases depending on where each of thecomponents are mounted on roller assembly 50. When magnet 90 is disposedon or within roller body 30 and Hall effect sensor 92 is disposed withinend cap 54, the distance between Hall effect sensor 92 and magnet 90changes as bushing 56 thins. As the distance between Hall effect sensor92 and magnet 90 changes, the magnetic field at Hall effect sensor 92changes and Hall effect sensor 92 produces a change in voltage.Alternatively, Hall effect sensor 92 or magnet 90 is disposed on bushing56. In each embodiment, the output voltage of Hall effect sensor 92indicates the change in bushing thickness. In another alternativeembodiment, monitoring device 58 includes a depth sensor to determinethe thickness bushing 56.

The temperature sensor and Hall effect sensor 92 within monitoringdevice 58 produce output signals or output data. The output frommonitoring device 58 is transferred to an external receiving devicewhich processes the signals or data output. A transmitter or connectionport is used to transfer signal or data output from monitoring device 58to an external receiving device, such as a computer. The transmitteddata can then be uploaded to a computer or other device which processesthe data. Data from monitoring device 58 is used to monitor theoperational condition of roller assembly 50. As monitoring device 58measures, for example, the temperature within the end caps 52 and 54 andthickness of bushing 56, the monitoring device produces output signalsor data which is transferred through a wireless transmitter to acomputer. Alternatively, the output data is accessed through a portwhich connects to monitoring device 58. The output data is processed andis used to determine if roller assembly 50 is operating at the propertemperature and bushing thickness. If the data indicates a problem withroller assembly 50, the problem can be recognized immediately. Forexample, if the temperature data indicates that the roller assembly hasreached an abnormally high temperature, a manual or automatic alarm istriggered. For example, a person can monitor the data and call theequipment operator when a roller assembly within the equipment reaches acertain temperature or becomes too hot. Alternatively, the computerincludes an algorithm that automatically triggers a warning indicator tothe equipment operator when a roller assembly reaches a certaintemperature. Similarly, if the Hall effect reaches a certain voltageindicating bushing wear, a manual or automatic alarm is triggered.Therefore, monitoring device 58 allows real-time feedback about thetemperature and bushing thickness for roller assembly 50.

Real-time monitoring of roller assembly 50 allows problems withlubricant and bushings to be addressed earlier and before damage toroller assembly 50 occurs. An operator is alerted when lubricant runsdry and stop the equipment before roller body 30 quickly wears throughbushing 56 causing premature failure of roller assembly. Lubricant cansimply be replaced or a lubrication system repaired, rather thanreplacing an entire damaged roller assembly. Bushing wear can bemonitored regularly and bushings 56 can be replaced before bushings 56are worn completely through and roller body 30 begins to grind into endcaps 52 and 54. Bushings can be replaced before damage to rollerassembly 50 is too substantial to be repaired. Monitoring device 58thereby provides a preventative monitoring and maintenance tool thatreduces maintenance costs in track undercarriages by detecting rollerproblems early and preventing premature roller failure.

FIG. 10 illustrates an alternative embodiment of a roller assemblyincluding a monitoring device disposed within the shaft. A portion ofroller assembly 100 is cut away in FIG. 10 to show internal componentsof roller assembly. Roller assembly 100 includes roller body 102, shaft104, end caps 106, and bushings 108. Roller body 102 rotates aroundshaft 104. Bushings 108 are pressed into roller body 102 such thatbushings 108 are fixed within roller body 102. Bushings 108 are rigidlyaffixed to inner surface 110 of roller body 102. Roller body 102 andbushings 108 rotate together around shaft 104, and therefore, aredynamic with respect to shaft 104. Roller body 102 can be metal, such ashigh strength steel, hardened steel, carbon steel, metal alloy, or othermaterial. In one embodiment, roller body 102 is hardened steel. Rollerbody 102 is monitored with the monitoring device disposed within rollerassembly 100 to detect wear within roller assembly 100 before rollerbody 102 is damaged. Roller body 102 rotates around fixed shaft 104.Shaft 104 is fixed within end caps 106. End caps 106 are rigidlyattached to or mounted to the undercarriage frame and shaft 104 ismounted to the undercarriage frame by end caps 106. End caps 106 can bemetal, including high strength steel, hardened steel, carbon steel,metal alloy, or other material.

Bushings 108 are disposed within roller assembly 100 to reduce thefriction between roller body 102 and shaft 104. Bushing 108 allowsroller body 102 to turn or rotate around shaft 104 without damagingroller body 102, bushings 108, or shaft 104. Bushings 108 includes innersurface 112 which contacts shaft 104. Bushing 108 can be metal,including copper, tin, zinc, nickel, iron, aluminum, or other metal orcan be metal alloy such as copper and tin, known as bronze, copper andzinc, or other metal alloy. In one embodiment, bushing 108 is bronze, anonferrous metal, and is a softer metal than roller body 102 and shaft104. A lubricant is disposed between shaft 104 and surface 112 ofbushing 108 to reduce the friction between shaft 104 and surface 112 ofbushing 108. In a self-contained lubrication system, lubricant is sealedinside roller assembly 100.

Openings 120 are formed partially through each end 122 of shaft 104.Openings 120 are formed parallel to the length of shaft 104 at a depthsufficient to overlap bushing 108. Openings 120 include a portion thatis oriented outwards toward a surface of shaft 104. Openings 120 therebyreach a surface of shaft 104 at a portion of shaft 104 near bushings108. Alternatively, openings 120 do not reach another surface of shaft104, but are formed through surface 122 of shaft 104 extending partiallythough shaft 104. Openings 120 may include a portion parallel to thelength of shaft 104 formed completely through shaft 104.

Monitoring device 124 is disposed within opening 120. Monitoring device124 includes one or more sensors to measure one or more physicalcharacteristics of bushing 108, shaft 104, roller body 102, and thelubricant. Opening 120 is formed with a diameter appropriate to fitmonitoring device 124. In one embodiment, the diameter of opening 120 isapproximately 1.8 centimeters (cm), or 0.7 inches. In an alternativeembodiment, opening 120 can be formed with a diameter greater than orless than 1.8 cm. Opening 120 is formed with a diameter large enough toaccommodate monitoring device 124. Opening 120 is formed such thatopening 120 does not degrade the strength and functionality of shaft104.

A monitoring device 124 is placed within each of openings 120 in closeproximity to bushings 108. Monitoring device 124 may include one sensoror multiple sensors. In one embodiment, multiple sensors areaccommodated within monitoring device 124 which is formed into one unitand fits within openings 120. In an alternative embodiment, additionalopenings similar to openings 120 are formed through shaft 104 toaccommodate multiple monitoring devices 124 or multiple sensors orcomponents of monitoring device 124. In another embodiment, componentsof monitoring device 124 are disposed on or within bushing 108, rollerbody 102, or end caps 106. Monitoring device 124 can be incorporatedinto a lubrication system in order to monitor the lubrication withinroller assembly 100. Alternatively, monitoring device 124 is separatefrom the lubrication system and can be incorporated into existing rollerassemblies.

Monitoring device 124 monitors a physical characteristic of rollerassembly 100 in order to detect a problem within roller assembly 100.Monitoring device 124 measures temperature of roller assembly 100 andthickness of bushing 108, determines the presence or absence oflubricant within roller assembly 100, and determines if bushing 108 hasbeen worn completely away. Monitoring device 124 includes a sensor suchas a Hall effect sensor, temperature sensor, particulate sensor,viscosity sensor, depth sensor, or other type of sensor. In oneembodiment, monitoring device 124 measures a temperature at a surface ofbushing 108 or a temperature within shaft 104. In an alternativeembodiment, monitoring device 124 measures thickness of bushing 108using a magnet and a Hall effect sensor. In another embodiment,monitoring device 124 includes both a temperature sensor and a Halleffect sensor with a magnet. The temperature sensor, Hall effect sensor,and magnet of monitoring device 124 fit within openings 120 in each end122 of shaft 104, respectively. Alternatively, shaft 104, roller body102, and bushing 108 are configured with additional openings or ports toaccommodate additional sensors and other components of monitoring device124.

In one embodiment of monitoring device 124, a temperature sensor is usedto determine the lubricant status within roller assembly 100. Increasedtemperature within roller assembly 100 is one indicator of inadequatelubrication of bushing 108. A temperature sensor is disposed within ormounted to roller assembly 100 to measure the temperature of rollerassembly 100 within roller body 102. When lubrication runs low or runsout, the friction between shaft 104 and inner surface 112 of bushing 108increases. Without lubricant, shaft 104 directly contacts inner surface112 of bushing 108. Shaft 104 and bushing 108 are metal, resulting inmetal on metal contact. The increased friction between shaft 104 andbushing 108 results in increased temperature at shaft 104 and bushing108 within roller assembly 100. The change in temperature caused byreduced lubrication or a lack of lubrication is detected by thetemperature sensor of monitoring device 124. The temperature sensor mayinclude a contact sensor, such as a thermocouple, thermistor, resistancetemperature detector (RTD), or a non-contact temperature sensor, such asan infrared heat sensor. In an alternative embodiment, monitoring device124 measures the viscosity of the lubricant to determine the quality oflubrication within roller assembly 100. In another embodiment,monitoring device 124 includes a particulate sensor to determine thequality of lubrication and amount of metal particulates within rollerassembly 100.

In one embodiment of monitoring device 124, Hall effect sensor 92 isused to measure a thickness of bushing 108 to determine the amount ofwear on bushing 108. Monitoring device 124 includes magnet 90 and Halleffect sensor 92. Hall effect sensor 92 is disposed within opening 120.In one embodiment, magnet 90 is disposed within opening 120 over Halleffect sensor 92 such that Hall effect sensor 92 is disposed betweenmagnet 90 and bushing 108. Bushing 108 is disposed between Hall effectsensor 92 and roller body 102. The magnetic field between magnet 90 androller body 102 passes through the non-ferrous bushing 108 in betweenmagnet 90 and roller body 102. The distance between roller body 102 andmagnet 90 determines a magnetic field at Hall effect sensor 92 which isconverted into a voltage by Hall effect sensor 92. The thickness ofbushing 108 determines the distance between roller body 102 and magnet90 because bushing 108 separates roller body 102 from shaft 104 wheremagnet 90 is located. The magnetic field between roller body 102 andmagnet 90 changes when bushing 108 wears down and becomes thinner androller body 102 moves closer to or farther away from magnet 90.Therefore, monitoring device with magnet 90 and Hall effect sensor 92detects the amount of wear on bushing 108 by indirectly measuring thethickness of bushing 108.

In an alternative embodiment of monitoring device 124, Hall effectsensor 92 is disposed on one side of bushing 108 and magnet 90 isdisposed on a side of bushing 108 opposite the side where Hall effectsensor 92 is disposed. Bushing 108 is disposed between magnet 90 andHall effect sensor 92. The magnetic field of magnet 90 passes throughbushing 108 and is sensed by Hall effect sensor 92. For example, Halleffect sensor 92 is disposed within opening 120 and magnet is notdisposed within opening 120, but is disposed in an opening formedthrough roller body 102 or is disposed on or within bushing 108. As thethickness of bushing 108 changes, the position of Hall effect sensor 92changes with respect to magnet 90. As Hall effect sensor 92 moves closerto or is positioned closer to magnet 90, the magnetic field increasesand the voltage produced by Hall effect sensor 92 increases. As Halleffect sensor 92 moves farther from or is positioned farther away frommagnet 90, the magnetic field decreases and the voltage produced by Halleffect sensor 92 decreases. Therefore, monitoring device with magnet 90and Hall effect sensor 92 detects the amount of wear on bushing 108 bydirectly measuring the thickness of bushing 108. In each embodiment,monitoring device 124 functions even while roller body 102 is moving orrotating. Monitoring device 124 produces output data which indicates thebushing thickness thereby reporting an operational state of bushing 108in real-time.

The temperature sensor and Hall effect sensor 92 within monitoringdevice 124 produce output signals or output data. The output frommonitoring device 124 is transferred to an external receiving devicewhich processes the signals or data output. A transmitter or connectionport is used to transfer signal or data output from monitoring device124 to an external receiving device, such as a computer. The transmitteddata can then be uploaded to a computer or other device which processesthe data. Data from monitoring device 124 is used to monitor theoperational condition of roller assembly 100 while roller assembly 100is in use. Real-time monitoring of roller assembly 100 allows problemswith lubricant and bushings to be addressed earlier and before damage toroller assembly 100 occurs.

Real-time monitoring of roller assembly 100 allows problems withlubricant and bushings to be addressed earlier and before damage toroller assembly 100 occurs. An operator is alerted when lubricant runsdry and stop the equipment before roller body 102 quickly wears throughbushing 108 causing premature failure of roller assembly. Lubricant cansimply be replaced or a lubrication system repaired, rather thanreplacing an entire damaged roller assembly. Bushing wear can bemonitored regularly and bushings 108 can be replaced before bushings 108are worn completely through and roller body 102 begins to grind intoshaft 104. Bushings can be replaced before damage to roller assembly 100is too substantial to be repaired. Monitoring device 124 therebyprovides a preventative monitoring and maintenance tool that reducesmaintenance costs in track undercarriages by detecting roller problemsearly and preventing premature roller failure.

FIG. 11 shows a partial view of an alternative embodiment of a rollerassembly with dual flanges and including a monitoring device. Rollerassembly 130 includes roller body 132, shaft 134, end caps 136, andbushings. Roller body 132 includes dual flanges 138. Roller body 132rotates around shaft 134. Roller body 132 can be metal, such as highstrength steel, hardened steel, carbon steel, or other metal. In oneembodiment, roller body 132 is hardened steel. Roller body 132 ismonitored with the monitoring device disposed within the roller assemblyto detect wear within the roller assembly before roller body 132 isdamaged. Roller body 132 rotates around fixed shaft 134. Shaft 134 isfixed within end caps 136. End caps 136 are rigidly attached to ormounted to the undercarriage frame and roller body 132 is mounted to theundercarriage frame by end caps 136. End caps 136 can be metal,including high strength steel, hardened steel, carbon steel, or othermetal. Opening 140 is formed partially through shaft 134 to provide amounting point for a monitoring device.

FIG. 12 shows a cross section of an alternative roller assembly 130 witha monitoring device disposed within the shaft. Openings 140 are formedthrough each end 142 of shaft 134. Monitoring device 144 fits withinopening 140 and is mounted within shaft 134. Monitoring device 144monitors the operational state of bushings 146.

Bushings 146 are pressed into roller body 132 such that bushings 146 arefixed within roller body 132. Bushings 146 are rigidly affixed to theinner surface of roller body 132. Roller body 132 and bushings 146rotate together around shaft 134, and therefore, are dynamic withrespect to shaft 134. Bushings 146 are disposed within roller assembly130 to reduce the friction between roller body 132 and shaft 134.Bushing 146 allows roller body 132 to turn or rotate around shaft 134without damaging roller body 132, bushings 146, or shaft 134. Bushings146 includes inner surface 148 which contacts shaft 134. Bushing 146 canbe metal, including copper, tin, zinc, nickel, iron, aluminum, or othermetal or can be metal alloy such as copper and tin, known as bronze,copper and zinc, or other metal alloy. In one embodiment, bushing 146 isbronze, a nonferrous metal, and is a softer metal than roller body 132and shaft 134. A lubricant is disposed between shaft 134 and surface 148of bushing 146 to reduce the friction between shaft 134 and surface 148of bushing 146. In a self-contained lubrication system, lubricant issealed inside roller assembly 130.

Openings 140 are formed partially through each end 142 of shaft 134.Openings 140 are formed parallel to the length of shaft 134 at a depthsufficient to overlap bushing 146. Openings 140 include a portion thatis oriented outwards toward a surface of shaft 134. Openings 140 therebyreach surface 150 of shaft 134 at a portion of shaft 134 near bushings146. Alternatively, openings 140 do not reach surface 150 of shaft 134,but are formed through surface 142 of shaft 134 extending partiallythough shaft 134. Openings 140 may include a portion parallel to thelength of shaft 134 formed completely through shaft 134.

Monitoring device 144 is disposed within opening 140. Monitoring device144 includes one or more sensors to measure one or more physicalcharacteristics of bushing 146, roller body 132, shaft 134, and thelubricant. Opening 140 is formed with a diameter appropriate to fitmonitoring device 144. In one embodiment, the diameter of opening 140 isapproximately 1.8 centimeters (cm), or 0.7 inches. In an alternativeembodiment, opening 140 can be formed with a diameter greater than orless than 1.8 cm. Opening 140 is formed with a diameter large enough toaccommodate monitoring device 144. Opening 140 is formed such thatopening 140 does not degrade the strength and functionality of shaft134.

A monitoring device 144 is placed within each of openings 140 in closeproximity to bushings 146. Monitoring device 144 may include one sensoror multiple sensors. In one embodiment, multiple sensors areaccommodated within monitoring device 144 which is formed into one unitand fits within openings 140. In an alternative embodiment, additionalopenings similar to openings 140 are formed through shaft 134 toaccommodate multiple monitoring devices 144 or multiple sensors orcomponents of monitoring device 144. In another embodiment, componentsof monitoring device 144 are disposed on or within bushing 146, rollerbody 132, or end caps 136. Monitoring device 144 can be incorporatedinto a lubrication system in order to monitor the lubrication withinroller assembly 130. Alternatively, monitoring device 144 is separatefrom the lubrication system and can be incorporated into existing rollerassemblies.

Monitoring device 144 monitors a physical characteristic of rollerassembly 130 in order to detect a problem within roller assembly 130.Monitoring device 144 measures temperature of roller assembly 130 andthickness of bushing 146, determines the presence or absence oflubricant within roller assembly 130, and determines if bushing 146 hasbeen worn completely away. Monitoring device 144 includes a sensor suchas a Hall effect sensor, temperature sensor, particulate sensor,viscosity sensor, depth sensor, or other type of sensor. In oneembodiment, monitoring device 144 measures a temperature at a surface ofbushing 146 or a temperature within shaft 134. In an alternativeembodiment, monitoring device 144 measures thickness of bushing 146using a magnet and a Hall effect sensor. In another embodiment,monitoring device 144 includes both a temperature sensor and a Halleffect sensor with a magnet. The temperature sensor, Hall effect sensor,and magnet of monitoring device 144 fit within openings 140 in each end142 of shaft 134 respectively. Shaft 134 can be configured withadditional openings or ports to accommodate additional sensors and othercomponents of monitoring device 144.

In one embodiment of monitoring device 144, a temperature sensor is usedto determine the lubricant status within roller assembly 130. Increasedtemperature within roller assembly 130 is one indicator of inadequatelubrication of bushing 146. A temperature sensor is disposed within ormounted to roller assembly 130 to measure the temperature of rollerassembly 130 within roller body 132. When lubrication runs low or runsout, the friction between surface 150 of shaft 134 and inner surface 148of bushing 146 increases. Without lubricant, surface 150 of shaft 134directly contacts inner surface 148 of bushing 146. Shaft 134 andbushing 146 are metal, resulting in metal on metal contact. Theincreased friction between shaft 134 and bushing 146 results inincreased temperature at shaft 134 and bushing 146 within rollerassembly 130. The change in temperature caused by reduced lubrication ora lack of lubrication is detected by the temperature sensor ofmonitoring device 144. The temperature sensor may include a contactsensor, such as a thermocouple, thermistor, resistance temperaturedetector (RTD), or a non-contact temperature sensor, such as an infraredheat sensor. In an alternative embodiment, monitoring device 144measures the viscosity of the lubricant to determine the quality oflubrication within roller assembly 130. In another embodiment,monitoring device 144 includes a particulate sensor to determine thequality of lubrication and amount of metal particulates within rollerassembly 130.

FIG. 13 illustrates further detail of a cross section of an alternativeroller assembly with a monitoring device disposed within the shaft. Inone embodiment of monitoring device 144, Hall effect sensor 92 is usedto measure a thickness of bushing 146 to determine the amount of wear onbushing 146. Monitoring device 144 includes magnet 90 and Hall effectsensor 92. Hall effect sensor 92 is disposed within opening 140. Magnet90 is disposed within opening 140 over Hall effect sensor 92 such thatHall effect sensor 92 is disposed between magnet 90 and bushing 146.Bushing 146 is disposed between Hall effect sensor 92 and roller body132. Hall effect sensor 92 responds to the magnetic field between magnet90 and roller body 132. In roller assembly 130, bushing 146 is typicallybronze, a similar copper alloy, or other alloy or metal. Roller body 132is typically hardened steel, or other type of steel or metal. Therefore,roller body 132 responds to magnet 90 and bushing 146 is unaffected bymagnet 90. The magnetic field between magnet 90 and roller body 132 isuninterrupted by the non-ferrous bushing 146 in between magnet 90 androller body 132. The distance between roller body 132 and magnet 90determines a magnetic field at Hall effect sensor 92 which is convertedinto a voltage by Hall effect sensor 92. The thickness T3 of bushing 146determines the distance between roller body 132 and magnet 90 becausebushing 146 separates roller body 132 from shaft 134 where magnet 90 islocated. The magnetic field between roller body 132 and magnet 90changes when bushing 146 wears down and becomes thinner and roller body132 moves closer to or farther away from magnet 90. Therefore,monitoring device with magnet 90 and Hall effect sensor 92 detects theamount of wear on bushing 146 by indirectly measuring the thickness ofbushing 146.

In an alternative embodiment of monitoring device 144, Hall effectsensor 92 is disposed on one side of bushing 146 and magnet 90 isdisposed on a side of bushing 146 opposite the side where Hall effectsensor 92 is disposed. Bushing 146 is disposed between magnet 90 andHall effect sensor 92. The magnetic field of magnet 90 passes throughbushing 146 and is sensed by Hall effect sensor 92. For example, Halleffect sensor 92 is disposed within opening 140 and magnet is notdisposed within opening 140, but is disposed in an opening formedthrough roller body 132 or is disposed on or within bushing 146. As thethickness of bushing 146 changes, the position of Hall effect sensor 92changes with respect to magnet 90. As Hall effect sensor 92 moves closeror is positioned closer to magnet 90, the magnetic field increases andthe voltage produced by Hall effect sensor 92 increases. As Hall effectsensor 92 moves farther from or is positioned farther away from magnet90, the magnetic field decreases and the voltage produced by Hall effectsensor 92 decreases. Therefore, monitoring device with magnet 90 andHall effect sensor 92 detects the amount of wear on bushing 146 bydirectly measuring the thickness of bushing 146. In each embodiment,monitoring device 144 functions even while roller body 132 is moving orrotating. Monitoring device 144 produces output data which indicates thebushing thickness thereby reporting an operational state of bushing 132in real-time.

The temperature sensor and Hall effect sensor 92 within monitoringdevice 144 produce output signals or output data. The output frommonitoring device 144 is transferred to an external receiving devicewhich processes the signals or data output. A transmitter or connectionport is used to transfer signal or data output from monitoring device144 to an external receiving device, such as a computer. The transmitteddata can then be uploaded to a computer or other device which processesthe data. Data from monitoring device 144 is used to monitor theoperational condition of roller assembly 130 while roller assembly 130is in use. Real-time monitoring of roller assembly 130 allows problemswith lubricant and bushings to be addressed earlier and before damage toroller assembly 130 occurs.

Real-time monitoring of roller assembly 130 allows problems withlubricant and bushings to be addressed earlier and before damage toroller assembly 130 occurs. An operator is alerted when lubricant runsdry and stop the equipment before roller body 132 quickly wears throughbushing 146 causing premature failure of roller assembly. Lubricant cansimply be replaced or a lubrication system repaired, rather thanreplacing an entire damaged roller assembly. Bushing wear can bemonitored regularly and bushings 146 can be replaced before bushings 146are worn completely through and roller body 132 begins to grind intoshaft 132. Bushings can be replaced before damage to roller assembly 130is too substantial to be repaired. Monitoring device 144 therebyprovides a preventative monitoring and maintenance tool that reducesmaintenance costs in track undercarriages by detecting roller problemsearly and preventing premature roller failure.

FIG. 14 illustrates an alternative embodiment of a roller assembly withan idler roller and including a monitoring device. Idler roller assembly160 constitutes a roller and includes idler body 162, shaft 164, endcaps 166, and bushings. Idler body 162 rotates around shaft 164. Idlerbody 162 can be metal, such as high strength steel, hardened steel,carbon steel, metal alloy, or other metal. In one embodiment, idler body162 is hardened steel. Idler body 162 is monitored with the monitoringdevice disposed within the roller assembly to detect wear within theroller assembly before idler body 162 is damaged. Idler body 162 rotatesaround fixed shaft 164. Shaft 164 is fixed within end caps 166. End caps166 are rigidly attached to or mounted to the undercarriage frame andidler body 162 and shaft 164 are mounted to the undercarriage frame byend caps 166. End caps 166 can be metal, including high strength steel,hardened steel, carbon steel, metal alloy, or other metal. Opening 168is formed through surface 170 of shaft 164 to provide a mounting pointfor a monitoring device.

FIG. 15 illustrates a cross section of an idler roller including amonitoring device. Bushings 172 are pressed into idler body 162 suchthat bushings 172 are fixed within idler body 162. Bushings 172 arerigidly affixed to the inner surface of idler body 162. Idler body 162and bushings 172 rotate together around shaft 164, and therefore, aredynamic with respect to shaft 164. Bushings 172 are disposed withinidler body 162 to reduce the friction between idler body 162 and shaft164. Bushing 172 allows idler body 162 to turn or rotate around shaft164 without damaging idler body 162, bushings 172, or shaft 164.Bushings 172 includes inner surface 174 which contacts shaft 164.Bushing 172 can be metal, including copper, tin, zinc, nickel, iron,aluminum, or other metal or can be metal alloy such as copper and tin,known as bronze, copper and zinc, or other metal alloy. In oneembodiment, bushing 172 is bronze, a nonferrous metal, and is a softermetal than idler body 162 and shaft 164. A lubricant is disposed betweenshaft 164 and bushing 172 to reduce the friction between shaft 164 andbushing 172. In a self-contained lubrication system, lubricant is sealedinside roller assembly 160.

Openings 168 are formed partially through each end 170 of shaft 164.Openings 168 are formed parallel to the length of shaft 164 at a depthsufficient to overlap bushing 172. Openings 168 include a portion thatis oriented outwards toward a surface of shaft 164. Openings 168 therebyreach surface 176 of shaft 164 at a portion of shaft 164 near bushings172. Alternatively, openings 168 do not reach surface 176 of shaft 164,but are formed through surface 170 of shaft 164 extending partiallythough shaft 164. Openings 168 may include a portion parallel to thelength of shaft 164 formed completely through shaft 164.

Monitoring device 178 is disposed within opening 168. Monitoring device178 includes one or more sensors to measure one or more physicalcharacteristics of bushing 172, idler body 162, shaft 164, and thelubricant. Opening 168 is formed with a diameter appropriate to fitmonitoring device 178. In one embodiment, the diameter of opening 168 isapproximately 1.8 centimeters (cm), or 0.7 inches. In an alternativeembodiment, opening 168 can be formed with a diameter greater than orless than 1.8 cm. Opening 168 is formed with a diameter large enough toaccommodate monitoring device 178. Opening 168 is formed such thatopening 168 does not degrade the strength and functionality of shaft164.

A monitoring device 178 is placed within each of openings 168 in closeproximity to bushings 172. Monitoring device 178 may include one sensoror multiple sensors. In one embodiment, multiple sensors areaccommodated within monitoring device 178 which is formed into one unitand fits within openings 168. In an alternative embodiment, additionalopenings similar to openings 168 are formed through shaft 164 toaccommodate multiple monitoring devices 178 or multiple sensors orcomponents of monitoring device 178. In another embodiment, componentsof monitoring device 178 are disposed on or within bushing 172, rollerbody 162, or end caps 166. Monitoring device 178 can be incorporatedinto a lubrication system in order to monitor the lubrication withinroller assembly 160. Alternatively, monitoring device 178 is separatefrom the lubrication system and can be incorporated into existing rollerassemblies.

Monitoring device 178 monitors a physical characteristic of rollerassembly 160 in order to detect a problem within roller assembly 160.Monitoring device 178 measures temperature of roller assembly 160 andthickness of bushing 172, determines the presence or absence oflubricant within roller assembly 160, and determines if bushing 172 hasbeen worn completely away. Monitoring device 178 includes a sensor suchas a Hall effect sensor, temperature sensor, particulate sensor,viscosity sensor, depth sensor, or other type of sensor. In oneembodiment, monitoring device 178 measures a temperature at a surface ofbushing 172 or a temperature within shaft 164. In an alternativeembodiment, monitoring device 178 measures thickness of bushing 172using a magnet and a Hall effect sensor. In another embodiment,monitoring device 178 includes both a temperature sensor and a Halleffect sensor with a magnet. The temperature sensor, Hall effect sensor,and magnet of monitoring device 178 fit within openings 168 in each end170 of shaft 164 respectively. Shaft 164 can be configured withadditional openings or ports to accommodate additional sensors and othercomponents of monitoring device 178.

In one embodiment of monitoring device 178, a temperature sensor is usedto determine the lubricant status within roller assembly 160. Increasedtemperature within roller assembly 160 is one indicator of inadequatelubrication of bushing 172. A temperature sensor is disposed within ormounted to roller assembly 160 to measure the temperature of rollerassembly 160 within idler body 162. When lubrication runs low or runsout, the friction between surface 176 of shaft 164 and inner surface 174of bushing 172 increases. Without lubricant, surface 176 of shaft 164directly contacts inner surface 174 of bushing 172. Shaft 164 andbushing 172 are metal, resulting in metal on metal contact. Theincreased friction between shaft 164 and bushing 172 results inincreased temperature at shaft 164 and bushing 172 within rollerassembly 160. The change in temperature caused by reduced lubrication ora lack of lubrication is detected by the temperature sensor ofmonitoring device 178. The temperature sensor may include a contactsensor, such as a thermocouple, thermistor, resistance temperaturedetector (RTD), or a non-contact temperature sensor, such as an infraredheat sensor. In an alternative embodiment, monitoring device 178measures the viscosity of the lubricant to determine the quality oflubrication within roller assembly 160. In another embodiment,monitoring device 178 includes a particulate sensor to determine thequality of lubrication and amount of metal particulates within rollerassembly 160.

FIG. 16 illustrates further detail of a cross section an idler rollerincluding a monitoring device. In one embodiment of monitoring device178, Hall effect sensor 92 is used to measure a thickness of bushing 172to determine the amount of wear on bushing 172. Monitoring device 178includes magnet 90 and Hall effect sensor 92. Hall effect sensor 92 isdisposed within opening 168. Magnet 90 is disposed within opening 168over Hall effect sensor 92 such that Hall effect sensor 92 is disposedbetween magnet 90 and bushing 172. Bushing 172 is disposed between Halleffect sensor 92 and idler body 162. Hall effect sensor 92 responds tothe magnetic field between magnet 90 and idler body 162. In rollerassembly 160, bushing 172 is typically bronze, a similar copper alloy,or other alloy or metal. Idler roller body 162 is typically hardenedsteel, or other type of steel or metal. Therefore, idler body 162responds to magnet 90 and bushing 172 is unaffected by magnet 90. Themagnetic field between magnet 90 and idler body 162 is uninterrupted bythe non-ferrous bushing 172 in between magnet 90 and idler body 162. Thedistance between idler body 162 and magnet 90 determines a magneticfield at Hall effect sensor 92 which is converted into a voltage by Halleffect sensor 92. The thickness of bushing 172 determines the distancebetween idler body 162 and magnet 90 because bushing 172 separates idlerbody 162 from shaft 164 where magnet 90 is located. The magnetic fieldbetween idler body 162 and magnet 90 changes when bushing 172 wears downand becomes thinner and idler body 162 moves closer to or farther awayfrom magnet 90. Therefore, monitoring device with magnet 90 and Halleffect sensor 92 detects the amount of wear on bushing 172 by indirectlymeasuring the thickness of bushing 172.

In an alternative embodiment of monitoring device 178, Hall effectsensor 92 is disposed on one side of bushing 172 and magnet 90 isdisposed on a side of bushing 172 opposite the side where Hall effectsensor 92 is disposed. Bushing 172 is disposed between magnet 90 andHall effect sensor 92. The magnetic field of magnet 90 passes throughbushing 172 and is sensed by Hall effect sensor 92. For example, Halleffect sensor 92 is disposed within opening 168 and magnet is notdisposed within opening 168, but is disposed in an opening formedthrough roller body 162 or is disposed on or within bushing 174. As thethickness of bushing 172 changes, the position of Hall effect sensor 92changes with respect to magnet 90. As Hall effect sensor 92 moves closeror is positioned closer to magnet 90, the magnetic field increases andthe voltage produced by Hall effect sensor 92 increases. As Hall effectsensor 92 moves farther from or is positioned farther away from magnet90, the magnetic field decreases and the voltage produced by Hall effectsensor 92 decreases. Therefore, monitoring device with magnet 90 andHall effect sensor 92 detects the amount of wear on bushing 172 bydirectly measuring the thickness of bushing 172. In each embodiment,monitoring device 178 functions even while roller body 162 is moving orrotating. Monitoring device 178 produces output data which indicates thebushing thickness thereby reporting an operational state of bushing 172in real-time.

The temperature sensor and Hall effect sensor 92 within monitoringdevice 178 produce output signals or output data. The output frommonitoring device 178 is transferred to an external receiving devicewhich processes the signals or data output. A transmitter or connectionport is used to transfer signal or data output from monitoring device178 to an external receiving device, such as a computer. The transmitteddata can then be uploaded to a computer or other device which processesthe data. Data from monitoring device 178 is used to monitor theoperational condition of roller assembly 160 while roller assembly 160is in use. Real-time monitoring of roller assembly 160 allows problemswith lubricant and bushings to be addressed earlier and before damage toroller assembly 160 occurs.

Real-time monitoring of roller assembly 160 allows problems withlubricant and bushings to be addressed earlier and before damage toroller assembly 160 occurs. An operator is alerted when lubricant runsdry and stop the equipment before roller body 162 quickly wears throughbushing 172 causing premature failure of roller assembly. Lubricant cansimply be replaced or a lubrication system repaired, rather thanreplacing an entire damaged roller assembly. Bushing wear can bemonitored regularly and bushings 172 can be replaced before bushings 172are worn completely through and roller body 162 begins to grind intoshaft 162. Bushings can be replaced before damage to roller assembly 160is too substantial to be repaired. Monitoring device 178 therebyprovides a preventative monitoring and maintenance tool that reducesmaintenance costs in track undercarriages by detecting roller problemsearly and preventing premature roller failure.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed is:
 1. A roller assembly for an undercarriage,comprising: a fixed roller component; a rotating roller componentcomprising a ferrous material; a bushing comprising a non-ferrousmaterial disposed between the fixed roller component and the rotatingroller component; and a magnetic sensor disposed in the fixed rollercomponent adjacent to the bushing.
 2. The roller assembly of claim 1,wherein the magnetic sensor contacts the bushing.
 3. The roller assemblyof claim 1, wherein the magnetic sensor includes a Hall effect sensorand a magnet.
 4. The roller assembly of claim 1, wherein the non-ferrousmaterial of the bushing extends continuously from the fixed rollercomponent to the rotating roller component.
 5. The roller assembly ofclaim 1, further including a temperature sensor disposed on the fixedroller component.
 6. The roller assembly of claim 1, wherein themagnetic sensor is configured to generate a voltage potentialproportional to a thickness of the bushing.
 7. A roller assembly for anundercarriage, comprising: a fixed roller component; a rotating rollercomponent; a bushing disposed between the fixed roller component and therotating roller component; and a magnetic sensor disposed on the fixedroller component adjacent to the bushing, wherein the magnetic sensorcontacts the bushing.
 8. The roller assembly of claim 7, wherein themagnetic sensor includes a Hall effect sensor and a magnet.
 9. Theroller assembly of claim 7, wherein the bushing extends continuouslyfrom the fixed roller component to the rotating roller component. 10.The roller assembly of claim 7, further including a lubricant disposedbetween the bushing and rotating roller component.
 11. The rollerassembly of claim 7, wherein the bushing is press fit into the fixedroller component.
 12. The roller assembly of claim 7, further includinga data transmitting device coupled to the magnetic sensor.
 13. A methodof monitoring an undercarriage, comprising: providing an undercarriagecomprising a bushing; and using a magnetic sensor disposed adjacent tothe bushing to determine a wear of the bushing by measuring a magneticfield using the magnetic sensor.
 14. The method of claim 13, furtherincluding determining the wear of the bushing by using the magneticsensor to determine a distance from a fixed roller component of theundercarriage to a rotating roller component of the undercarriage. 15.The method of claim 13, further including reporting an operational stateof the bushing in real time by outputting data from a monitoring devicecoupled to the sensor.
 16. The method of claim 13, wherein the magneticsensor includes a Hall effect sensor disposed adjacent to the bushing.17. The method of claim 16, further including measuring a magneticeffect of a ferrous part of the undercarriage using the Hall effectsensor, wherein the bushing is disposed between the Hall effect sensorand the ferrous part of the undercarriage.
 18. A method of determiningwear of a bushing, comprising: disposing a bushing between a firstroller component and a second roller component; and using a sensordisposed adjacent to the bushing to determine a wear of the bushing bymeasuring a distance from the first roller component to the secondroller component.